Anti-icing gasoline composition

ABSTRACT

GASOLINE COMPOSITION HAVING A MAJOR FRACTION OF GASOLINE AND, AS AN ANTI-ICING AGENT, AN EFFECTIVE AMOUNT OF AN ADDITIVE COMPRISING, BY WEIGHT, ABOUT 0-30% ROSIN ACID AND ABOUT 70-100% OF A MIXTURE COMPRISING 3070% DIMER ACID AND 30=70% TRIMER ACID, FOR EXAMPLE, AN ADDITIVE CONSISTING ESSENTIALLY OF 12% OF ROSIN ACID AND 88% OF A MIXTURE COMPRISING 43% LINOLEIC ACID DIMER ACID AND 57% LINOLEIC ACID TRIMER ACID.

United States Patent O 3,834,882 ANTI-ICING GASOLINE COMPOSITION Bruce Hollis Garth, Newark, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del. No Drawing. Filed Oct. 6, 1972, Ser. No. 295,657 Int. Cl. C101 1/18 US. CI. 44-66 9 Claims ABSTRACT OF THE DISCLOSURE Gasoline composition having a major fraction of gasoline and, as an anti-icing agent, an effective amount of an additive comprising, by weight, about 30% rosin acid and about 70-100% of a mixture comprising 30- 70% dimer acid and 30-70% trimer acid, for example, an additive consisting essentially of 12% of rosin acid and 88% of a mixture comprising 43% linoleic acid dimer acid and 57% linoleic acid trimer acid.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a gasoline composition which provides carburetor anti-icing protection in internal combustion engines.

2. Description of the Prior Art When carburetted internal combustion engines are operated on a gasoline fuel having satisfactory volatility properties for cold weather, engine stallings may be encountered, particularly on damp days when the temperature is in the range 22-50 F. and the relative humidity is about 65%. Such engine stalling is generally attributed to the formation of ice on the throttle plate and on the surrounding carburetor wall. The formation of ice deposits restricts the passage of air into the carburetor, particulaly when the throttle plate is in the closed position, such as under idling conditions. Although engine stalling due to carburetor icing is a temporary condition, such stalling being eliminated when the engine reaches normal operating temperature, it is inconvenient for the driver, it is wasteful of fuel because of the repeated engine startings which are required and it may present driving hazards. Although carburetor icing can be avoided through use of means for heating the carburetor, it is generally recognized that the inclusion of an anti-icing additive in the motor fuel is the most effective method of overcoming the problem. Anti-icing additives in the art include water soluble polar compounds, such as methanol, ethanol, isopropanol, dimethylformamide, ethylene glycol and propylene glycol. These additives confer anti-icing protection by functioning as antifreezes, that is, by lowering the freezing point of water. Other additives in the art include compounds which modify the surface characteristics of either the water droplets or the metal surfaces of the carburetor so that the formed ice is prevented from adhering to the metal surfaces. Such additives are exemplified by long chain amines, amides and amine-carboxylate salts. The additives suggested in the art may not be acceptable commercially for one or more of the following reasons: 1) economically impractical amounts are required, particularly with the additives which function as antifreezes, (2) water interaction properties are poor, that is, the additives are readily extracted out of the gasoline during contact with water, such contact with water usual- 1y being unavoidable during storage and transportation of the gasoline, (3) the additives are costly to produce, either because of the nature of the syntheses or because of the unavailability of starting materials, and (4) the additives are monofunctional in that they function only as antiicing additives, whereas for convenience and economy it 3,834,882 Patented Sept. 10, 1974 is desirable that an additive be multifunctional, that is, in addition to providing anti-icing protection it should provide some other protective action, such as anti-rust protection.

US. 2,631,979 discloses the use of polymerized linoleic acid, especially the dimer thereof, as a rust inhibitor for oils, motor fuels, emulsions, polymers, polishes, paints and sprays. US. 2,632,695 discloses the use of polymerized C1648 unsaturated monocarboxylic acids, especially the dimers thereof, as rust inhibitors for mineral oil products such as gaoline, naphthas and burning oils. US. 2,686,713 discloses the use of tall oil and polymerized tall oil as rust inhibitors for fuel fractions of mineral oil. Tall oil is a by-product of the sulfate method of paper manufacture and contains saturated and unsaturated fatty acids and rosin acids. US. 3,667,152 discloses the use of tall oil fatty acids in turbine and diesel fuels as a wear inhibitor. US. 3,336,123 discloses a gasoline containing as an anti-stalling agent a neutral salt of a dialkylaminopropylcarboxamide and the dimer or trimer of linoleic acid. It also discloses that the individual components of the salt are ineffective as anti-stalling agents.

SUMMARY OF THE INVENTION It is an object of this invention to provide a gasoline composition which exhibits anti-icing characteristics when used in carburetted internal combustion engines. It is a further object to provide such a gasoline which contains only a small amount of a readily and economically available anti-icing additive. Still another object is to provide such a gasoline which additionally provides anti-rust protection. In summary, the invention resides in a gasoline composition having a major fraction of gasoline and, as an anti-icing agent, an effective mount of an additive comprising, by weight, about 030% of rosin acid and about 70-100% of a mixture comprising 30-70% dimer acid and 30-70% trimer acid. Preferred additives contain about 5-15% of rosin acid. Also preferred are additives containing acid mixtures having 40-60% dimer acid and 40- 60% trimer acid.

BRIEF DESCRIPTION OF THE INVENTION The invention resides in the discovery that certain dimer-trimer acid mixtures, optionally containing a limited amount of rosin acid, are very effective anti-icing additives for gasoline. The definition of the invention has been given above. Dimerized and trimerized fatty acids are well known in the art as anti-corrosion additives for lubricating oils and hydrocarbon fuels. Dimerized and trimerized fatty acids are prepared from polyunsaturated monocarboxylic acids. Upon dimerization, a dibasic or dicarboxylic acid is formed; upon trimerization, a tribasic or tricarboxylic acid is formed. Descriptions of the preparation and properties of dimerized and trimerized acids can be found, for example, in Journal of the American Oil Chemists Society, 24, 65-68 (1947); and in US. 2,482,761; 2,631,979; and 2,632,695. As shown in the art, the dimerized acid, also known as dimer acid, can be prepared by heating an unsaturated fatty acid in the presence of a small amount of water at a temperature of 260-360 C. for 3-8 hours. The dimer acid thus produced will usually contain some trimerized acid, also known as trimer acid. The amount of trimer acid can be increased, if desired, by varying the reaction conditions, for example, by employing higher temperatures and/or longer heating periods. Dimer and trimer acids can be formed from a polyunsaturated fatty acid as well as from a mixture of monounsaturated and polyunsaturated fatty acids. For example, amixture of oleic acid and linoleic acid produces dimer acid which includes the dimer of linoleic and oleic acids. Because of their availability and low cost, the C unsaturated aliphatic monocarboxylic acids generally are employed to produce dimer and trimer acids. The preferred dimer and trimer acids are those produced from linoleic acid and contain, respectively, 36 and 54 carbon atoms. Dimer and trimer acids derived from linoleic acid are readily available. Commercially available dimer acids may contain 40- 95% dimer acid. Similarly, commercially available trimer acids may contain 50-95% trimer acid. Such materials which are employed herein must be chosen so that the mixture of dimer and trimer acids will comprise 30-70 weight percent dimer acid and 30-70 weight percent trimer acid.

Rosin acids (also known as resin acids) are commercially available and are obtainable from oleoresins from pine trees; they also are known components of tall oil acids. They are primarily alkylor alkenyl-substituted hydrophenanthrene monocarboxylic acids wherein various isomeric forms of abietic acid constitute the major components.

Excellent carburetor anti-icing protection is obtained when the above defined composition is incorporated into gasoline at a low concentration. The amount added to the gasoline will vary with the particular additive, the nature of the gasoline and the degree of anti-icing protection desired. For example, winter grade gasolines vary in their volatiles content and those which are higher in volatiles content are more apt to produce carburetor icing. Hence, for such gasolines larger amounts of the antiicing composition are required. Usually, the amount of additive employe is 2-100 pounds per 1,000 barrels of gasoline (0.0008-0.04 weight percent). Generally, employing mixtures of dimer acid and trimer acid, that is, without rosin acid, at 25-30 pounds per 1,000 gallons of gasoline (0010-0012 weight percent), effective anti-icing is achieved with a gasoline having a 50% distillation point within the range 170-215 C. (according to ASTM Method D-86). It has been discovered that smaller quantities of additive are require with dimer-trimer-rosin acids as defined above. With such additives the amounts employed generally are 2-20 pounds per 1,000 gallons of gasoline (00008-0008 weight percent), preferably -20 pounds per 1,000 gallons (0004-0008 weight percent).

In summary, the present invention provides a gasoline composition which exhibits excellent carburetor antiicing properties. The anti-icing additive of the present invention: (1) is effective at low concentrations, (2) is economical, since dimer, trimer and rosin acids are readily available at low cost, (3) provides good water interaction properties, and (4) provides anti-corrosion protection in addition to anti-icing protection.

Examples 1-11 The anti-icing properties of the compositions described above were determined by adding the desired amount of the composition to gasoline and using the gasoline in the Engine Carburetor Anti-icing Test which was carried out on a Chevrolet 230 cubic inch, 6 cylinder engine equipped with a Stromberg type carburetor. The environment of the carburetor was maintained at 40 F. and 95% relative humidity. Thus, essentially water saturated, cool air was drawn through the carburetor. The test consisted of running the engine on a two-part cycle, namely, secends with open throttle at an engine speed of 1,600 rpm. and 10 seconds with the throttle almost closed at 400 rpm. (idling speed). During the test, ice forms on the throttle plate and on the surrounding carburetor walls. The ice causes the engine to stall by blocking the flow of air when the throttle plate is almost closed during the idling portion of the test. The base gasoline was chosen so that, normally, in the absence of an eifective anti-icing additive, engine stalling occurred after about 3-5 cycles. An additive is considered to be effective if it prevents stalling to about 10 cycles; an excellent anti-icing agent prevents stalling to at least about cycles. The base gasoline used in the anti-icing test had a 50% distillation .4 point of 197 F. according to ASTM Method D-86. The results are summarized in the following table wherein the concentrations of the anti-icing agents used are given in pounds per thousand barrels of gasoline.

Examples 6, 7 and 11-14 demonstrate the use of an effective amount of the anti-icing composition.

Example 12 This example demonstrates the good water interaction properties of the dimer-trimer-rosin acid composition described above. United States Federal Water Contact Test, Test Method Standard 791B-Method 3251.7, was employed wherein gasolines containing the test additives were shaken with aqueous phosphate buffer solution and the nature of the interface was observed. Numerical ratings were given to the interface characteristics as follows: (1) clear clean interface; (1b) a few small clear bubbles covering not more than estimated 50% of the interface and no shreds, lace and/or film at the interface; (2) shred of lace and/or film at interface; (3) loose lace and/or slight scum; and (4) tight lace and/or heavy scum.

TABLE II.FEDERAL WATER CONTACT TEST Additive Lb./1,000 bbl. Rating Dimer acid 40 2 Trimer acid b 4O 4 Dimer-trimer-rosin acids 0 16-16-4. 3 1b a Commercial dimer acid containing 0 dibasie acid 75 C tribasic acid (25%); Q18 monobasic acid (trace). M

0orr 1merc1al trimer acid containing 0 6 dibasic acid (10%); C 4 tribasie acid v Anti-icing composition of this invention.

What is claimed is:

1. Gasoline composition having a major amount of a component boiling in the gasoline range and, as an antiicing agent, an effective amount of an additive comprising, by weight, about 5-30% of rosin acid and about 70- of a mixture comprising 30-70% dimer acid and 3070% trimer acid.

2. The composition of Claim 1 wherein the dimer acid and trimer acid are produced from a C unsaturated aliphatic monocarboxylic acid.

3. The composition of Claim 2 wherein the dimer acid is linoleic acid dimer acid and the trimer acid is linoleic acid trimer acid.

4. The composition of Claim 2 wherein the additive contains 5-15 of resin acid.

5. The composition of Claim 2 wherein the dimer- References Cited trimer acid mixture is comprised of 4060% dimer acid UNITED STATES PATENTS and 40-60% trimer acid.

6. The composition of Claim 2 which contains 0.0008- 2,632,695 3/1953 Lanfhs et Q04 weight percent of additive 5 2,686,713 8/1954 Whlt Ct 211. 44-66 Qf Q gZSQZ L ZfigQ 6 Whlch mntams PATRICK P. GARVIN, Primary Examiner 8. The composition of Claim 4 which contains 0.0008- Y. H. SMITH, Assistant Examiner 0.008 weight percent of additive.

9. The composition of Claim 8 which contains 0.004- 10 U.S. Cl. X.R.

0.008 weight percent of additive. 44DIG 1, 70 

